A population-based case-control epidemiologic study will be conducted to investigate risk factors associated with the incidence of salivary gland cancer. Incident cases of salivary gland cancer, diagnosed between October 1, 1990 and December 31, 1993, will be identified through rapid case ascertainment systems established under the auspices of two of the California Tumor Registry regional registries. The cases, who will number approximately 285, will be compared to an equal number of controls selected randomly from the general population and frequency-matched to the cases on the basis of five-year age groups. Controls age 20-64 will be identified through random-digit dialing processes. Controls age 65-79 will be identified through the records of the Health Care Finance Administration. Telephone interviews will be conducted using a structured questionnaire administered by a trained interviewer. The questionnaire will include items covering exogenous exposures, medical history, and selected dietary,k lifestyle, and sociodemographic factors. An independent pathology review will be conducted to provide a uniform histologic classification and to distinguish primary cancers from metastases when there is a prior history of cancer. Multiple logistic regression analyses will be performed in order to assess the effects of each factor while taking all other factors into account and to assess effect modification. The results should elucidate the little known etiologic factors associated with the development of salivary gland cancer and help to explain the recently observed increasing incidence of these cancers.